The walls of a refrigerator are typically constructed by sandwiching a layer of insulation between sheet metal panels. Consider a wall made from fiberglass insulation of thermal conductivity k=0.046 W/m*K and thickness L₁= 50 mm and steel panels, each of thermal conductivity kp=60 W/m*K and thickness Lp= 3 mm. If the wall separates refrigerated air at To, 4°C from ambient air at T∞,o=25°C, what is the heat gain per unit surface area?Coefficients associated with natural convection at the inner and outer surfaces may be approximated as ho=h;=5 W/m*K.